[Miguel]

I don`t think any of the modern lenses is bad wide open. I think nailing focus and having enough depth of field are more relevant than how sharp the lens is wide open. I use the largest aperture keeping AF / DoF ok,

Yes this is spot on. It's more the responsibility of the photographer to work the tool to ensure the shot is well executed. DOF management is the key here. Some folks conflate depth of field with sharpness.

M

[Rondec]

I think it depends on the lens. I feel like the FA 77 and DA *55 are pretty sharp wide open. The FA 31 I like stopped down to f2.4. I used to own the FA 50 f1.4 and I wouldn't shoot it wider than f2.8.

Any time you shoot wide open, you deal with lower contrast and narrow depth of field. I certainly prefer having the ability to open the lens wider if I want to.





Both of these were shot at f1.6 on the DA *55.

[kh1234567890]

What's your view ?

My M50/f1.4 is pretty useless at f1.4 unless you are very careful with the subject and light or like the 'dreamy' look. Stopped down just a touch, or used with a step down ring as a hood to effective f1.7 or thereabouts it is a different story - it is certainly as good or better than my A50/f1.7 wide open. And it'd only cost me £30 ($50)

[Sagitta]

Due to circumstance, I can't shoot much higher than f/4.

This limits me for now to a handful of my lenses, none of which (save one) were even remotely expensive.

Wide apertures are incredibly useful when you need isolation or don't have the time (or ability) to get your sensor clean in the event of problems.

As far as clarity goes, I don't really have issues with fuzziness. If its a touch fuzzy, simply beat it up with some selective post and/or reduce the image size and you're usually set.

Here are some recents, all wide open (or at most a stop down) at whatever the minimum aperture was for the lens.







As someone mentioned, a lot of times people mistake a narrow depth of field for an image not being sharp. IMHO, if you can't manual focus with a narrow DOF or your more modern lens isn't autofocusing spot-on, then a wide aperture lens would very much be useless.

I've discovered over the past year however that even 'trash' lenses tend to still be sharp even stopped down, or at least are sharp enough for most uses. Of course if you're going in to view them at 100% and pixel peep, then you'll probably have issues with almost any photo.

[lesmore49]

Some risible claptrap right there. The guy had a practical question; what he gets instead is pseudoprofound malarkey.

X 2

Les

[timo]

I have some fast lenses...F 1.4, F 1.8, etc. I rarely shoot them at F 1.4, 1.8 due to sharpness.

I think it's great to have an F 1.8....but if the sharpness ain't there (in my view) till about F 3.5....maybe F 2.8....I've never been able to see the value, especially for advanced amateur photography.

I understand the bokeh thing.

I wonder if...really fast lenses....say F 1.4 to F 1.8 at these F stops....are worth it, particularly in these days of ever increasing ISO....with ever decreasing noise....or grain as we used to call it.

What's your view ?

While all lenses are a bit softer than optimal wide open, the softness of fast lenses, with associated background fuzziness, gives you creative opportunities, particularly with people shots, but also atmospheric landscapes and townscapes, or flowers, say. You don't want super-sharpness with a dreamy portrait or flower shot. You do need to make sure the right part of the subject is in focus (which can be challenging) - but that's a different topic.

[Sandy Hancock]

+1 to timo.

I like what fast lenses do wide open. Although it is quite sharp in the centre, my A50/1.2 does some funky stuff elsewhere in the frame at f/1.2, and the depth of field is insanely thin. Stop it down to 1.6 and it is just a well behaved, razor sharp fast fifty well before anyone can even use a f/2.8 numpty.

Same goes for my FA31, DA*55 and FA77.

[Digitalis]

Remember, a decent f/1.4 lens is also an excellent f/5.6 lens - by f/8 most 50mm lenses perform identically.


Pentax K5IIs - SMCP-K 50mm f/1.2 @ f/1.2


Pentax K5IIs - SMCP-FA31mm f/1.8 ASPH Limited @ f/1.8


Pentax K10D - SMCP-FA 77mm f/1.8 Limited @ f/1.8

Fast lenses typically hit their peak performance at wider apertures than slower lenses do, so you can comfortably sit beneath the diffraction limit. Also faster lenses allow for a brighter viewfinder and give you freedom to hand hold your camera where using a slower lens would require more rigid means of support.

[8540tomg]

As a manual lens man, a bright viewfinder is everything for me especially when used with a Katzeye screens.

+1 on this point. Much easier to focus my faster old primes than the slower ones.

There is no substitute for speed on this score.

Tom G

[Nicolas06]

I have some fast lenses...F 1.4, F 1.8, etc. I rarely shoot them at F 1.4, 1.8 due to sharpness.

I think it's great to have an F 1.8....but if the sharpness ain't there (in my view) till about F 3.5....maybe F 2.8....I've never been able to see the value, especially for advanced amateur photography.

I understand the bokeh thing.

I wonder if...really fast lenses....say F 1.4 to F 1.8 at these F stops....are worth it, particularly in these days of ever increasing ISO....with ever decreasing noise....or grain as we used to call it.

What's your view ?

Some lens are very sharp wide open and can be said as being fast.

On pentax this is the case of theses lenses: DA35 f/2.4, FA31 f/1.8 or FA35 f/2, DA70 f/2.4.
Going for sigma this is Sigma Art 35mm, Sigma Art 50mm, Sigma 85mm f/1.4 are really sharp too wide open. And Samyang 35mm is fantastic.

By f/2.8 all high end lenses tend to be sharper than one need expcepted if thinking of printing 30x40 or doing heavy crops.

Even if you lens is not perfectly sharp at f/2, the rendering is different and the softness can even be a feature. You don't want to see all the features, hair or pores of a woman portrait anyway. And even if you want it, the woman doesn't.

As for high iso, if the scene you shoot can cope with the apperture, there is really a dramatic difference between a shoot at 800-1200 isos at f/2 than with 2500-3000 isos at f/3.5... The noise start to be very visible and all color deph is lost.

[SpecialK]

Seen this before and never seen anyone point out that, the faster the lens, the faster the optimal aperture probably is.

Three posts up from yours :-)

[jrpower10]

Three posts up from yours :-)

Right you are. Guilty of skimming too much

[ivanvernon]

I have always considered that large aperture lens (f 0.95, f 1.0, f 1.2, f 1.4, or really any aperture larger than f 2.0) have three advantages, all of them creative advantages:

1. Their narrow DOF allows creative isolation that permits focussing attention on one part of a field, while still showing the larger field of view partially OOF. kh1234567890's steel railing photo in this thread being a good example. That photo is not about the people in the shot nor about the stream; it is about the railing, but you can also see where the railing is and even understand something about its purpose. If everything in that photo were actually in focus, as would be the case at perhaps f 8.0, then it would be an entirely different photo telling an entirely different story.

2. Their low light performance permits photos that might not otherwise be possible. I find this particularly valuable in low-light portraiture.

3. They permit wonderfully abstract, blurred backgrounds, permitting full isolation of the subject. This aspect can be quite useful when taking a photo of something that has a background that is distracting or otherwise inappropriate to the subject. In studio contexts, you can use some type of back drop to achieve a similar purpose, but (at least not so easily) outside.

Well, that is my take on the matter, nothing new that has not been said, but just a recapitulation. All that being said, there are probably more inept uses of these characteristics of large aperture lenses than skillful uses. I find that it is quite challenging to use large apertures and their shallow DOFs from both a technical standpoint (getting the things in foucus that you want to have in focus) and from an artistic standpoint (was kh1234567890's railing photo a worthwhile effort, i.e., was there any real artistic purpose served by isolating the railing?) I think yes, but someone else might think, that well, that is just a railing, why bother telling its story? One thing that separates good photos from great ones is the artistic success of the photo--and about that point photographers and wider audiences may well have different opinions.

[kh1234567890]

I think that the ability to isolate the subject is the best feature of wide aperture lenses. Light gathering capacity used to be important with film, when we could only dream of being able to shoot at say ISO 6400 and still end up with a recognisable image, but modern sensors have largely negated that need. There is a limit to how fast you want a lens to be, there is a point at which the shallow depth of field can become distractive and annoying. And of course the depth of field depends on the focal length and the subject distance. For 50mm f1.4-f1.8 feels about right.

I would rather have a lens which is useable wide open than one which claims to be, or is, faster but is so soft and fuzzy wide open that you have to stop it down in practice. You just end up carting about an extra weight of glass. Pentax had got it right with the Limited lens series - they are not the fastest around at their focal lengths but are eminently useable wide open and are small and light.




DA70 Ltd at f2.4